[RE-wrenches] Stainless Steel Cable Ties
frenergy
frenergy at psln.com
Thu Apr 25 20:45:52 PDT 2013
Jason is the only one that's mentioned brands of zip ties. Holy Smokes all the conversation seems be discussing black plastic zip ties like they are all the same. I found some T & B black zip ties (Grainger, I think) that make the ones in Home Despot look like skinny tissue paper. If you look for "Heavy Duty", you can choose from tensile strengths, widths, thickness, UV resistance, temperature, made in USA (or not).... just a thought.
Bill
----- Original Message -----
From: Ray Walters
To: RE-wrenches
Sent: Thursday, April 25, 2013 12:23 PM
Subject: Re: [RE-wrenches] Stainless Steel Cable Ties
Terrible. I've got a file of pics like that, and the wires can grab hold of something while the tracker rotates, and rip a j box right off the back of the module.
Around here, the white zip ties don't even last long enough just sitting in the truck to install without breaking.
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760On 4/25/2013 11:19 AM, August Goers wrote:
Ray,
Your points all seem good. And I echo the other comments that white non-UV zip ties should never be used. I bumped into a tracker installation a few weeks ago out in the Fresno area with very poor wire management! See attached pic - I have no idea who installed the system or when. It looks like the wire management was never any good in the first place although if you zoom in you'll see traces of a few white zip ties here and there that seem to be falling apart.
We've managed to get our rooftop installations to be completely managed with stainless s-clips and then maybe just a couple black plastic zip ties in critical locations. So far so good. A lot of it just goes back to good craftsmanship and running the PV wire in strategic locations so it's mostly supported by channel or rail. A tracking system is a completely different story where the wires will be moving as the system tracks. Plastic zip ties clearly don't seem like a good idea for tracking applications.
Best,
August
From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Ray Walters
Sent: Thursday, April 25, 2013 9:30 AM
To: Solar Energy Solutions; RE-wrenches
Subject: Re: [RE-wrenches] Stainless Steel Cable Ties
Black UV resistant ties only last a few years at altitude in New Mexico and Colorado. UV is brutal, and causes PVC conduit to discolor within 2 years. The zips will actually hold for 10+ years, but aren't really strong. I've come back on my own work, and just yanked on them, and popped them right off.
They just get very brittle. If on a tracker that is constantly pulling on them, they'll be trash on the ground after less than 5 years. I use wire loom clamps with rubber insulators in those cases, and then the zip ties just hold the bundle of wires together, but aren't actually securing the wire to the structure.
I looked into this recently for a large PV installation company and I found that Nylon 6.6 is probably the best, but the specified design life of the zip when exposed to UV was 6 to 10 years. We found a nylon zip rated to over 15 years, but it was special order and cost something like $2/ ea (cough, cough)
I like the idea of SS ties, but they are not the same as the SS clips as mentioned. The clips have curved edges that won't cut into the cables. USE wire actually is pretty easy to cut into, and I've seen a few shorts due to metal cutting into it. ( module edges, romex type connectors, etc) I would wrap the wire with a thick electrical tape before zip tieing with SS ties. There is a heavy mil pipe wrap tape (UV and underground rated) that plumbers use on gas lines.
R.Ray WaltersCTO, Solarray, IncNabcep Certified PV Installer, Licensed Master ElectricianSolar Design Engineer303 505-8760On 4/25/2013 9:48 AM, Solar Energy Solutions wrote:
We have used black cable ties since 1987 to strap sensor wire to PVC pipe for our solar pool heating systems. I was just at a system we installed in 1989 mounted on an East facing roof yesterday. The exposed 20g sensor wire still had intact and plyable sheilding and the black cable ties still firmly attached and not brittle. We have other similiar scenes with systems mounted on South facing roof were the black cable ties are still in tact under full solar exposure... for Portland Oregon. Yanking on some of these cable ties sometimes break the ancient tie. But, more often than not, as yesterday, we have to break out our wire cutters to accomplish this task.
Thus, I gotta think that black cable ties under a PV array which are not exposed to any of the heat or sun we usually subject them to... are going to last an even longer time.
Andrew Koyaanisqatsi
President
Solar Energy Solutions, Inc.
Since 1987,
Moving Portland and Beyond
to an Environmentally Sustainable Future.
503-238-4502
http://www.solarenergyoregon.com/
"Better one's House too little one day
than too big all the Year after."
From: Chris Mason <cometenergysystems at gmail.com>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Sent: Thursday, April 25, 2013 8:12 AM
Subject: Re: [RE-wrenches] Stainless Steel Cable Ties
Make sure you use black cable ties, the white ones fail in UV from sunlight.
On Thu, Apr 25, 2013 at 11:06 AM, August Goers <august at luminalt.com> wrote:
I too share the concern about standard plastic zip ties. However, I started in the industry in 1997 and have yet to see zip ties that are falling apart. Does anyone on the list have firsthand experience with failed plastic zip ties?
Best,
August
August Goers
Luminalt Energy Corporation
1320 Potrero Avenue
San Francisco, CA 94110
m: 415.559.1525
o: 415.641.4000
august at luminalt.com
From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Solarguy
Sent: Thursday, April 25, 2013 7:08 AM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] Stainless Steel Cable Ties
We have used 8" flat SS ties for years and I have no concern about the wear on the conductor insulation. They are long enough to circle a standard Unirac rail and several wires leaving 1" or so tag end. Needle nose pliers work to twist the end and snug down the tie as tight as you're comfortable with. The metal tie, once bent around the corners cannot stretch any tighter, unlike nylon, regardless of how tightly you twist the pliers. As for the edges, quality ties are not sharp. Or cheap.
Jim Duncan
North Texas Renewable Energy Inc
http://www.ntrei.com/
NABCEP PV 031310-57
TECL-27398
ntrei at 1scom.net
817.917.0527
From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Jason Szumlanski
Sent: Thursday, April 25, 2013 8:08 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Stainless Steel Cable Ties
There was a recent thread about wire management. Heyco SunBundler ties have a vinyl coating. I recommended the clips from PV Racking that are stainless steel coated in rubber. I've had the same concern, and both of these seem like good solutions to me.
Jason Szumlanski
Fafco Solar
On Thu, Apr 25, 2013 at 1:20 AM, Benn Kilburn - DayStar Renewable Energy <benn at daystarsolar.ca> wrote:
Wrenches,
I searched the archives, but came up with nothing on this..
I have found a good supplier for reasonably priced stainless steel cable ties and have been using them in place of black nylon cable ties for supporting cables, PV wires and micro-inverter wires to the mounting rails and such. I feel better knowing the wires under the array are supported this way rather than with plastic/nylon cable ties, for which I tried but cannot get a manufacturer to guarantee will last 20+yrs.
A colleague is questioning this method (SS ties) with the concern that over time the (albeit small) movement in the wires and/or expansion/contraction of the rails could result in the stainless steel cable ties cutting thru the wire's insulation and then...
I have heard this concern before from others as well.
The way I see it is that the very popular stainless steel "S" cable clips that hold wires to module frames have comparable equal sharp edges as well and would pose the same risk, but there doesn't seem to be any concern there.
I am wondering who else is using SS ties in place of nylon ones, and if you are taking additional steps to protect the wire's insulation from the SS ties?
Common sense abides, meaning don't wrap a wire around the SS ties so that the wire has tension on the sharp edge of the tie. Flat edge contact with the wire only, the same way that you wouldn't run a wire across/around a sharp cut edge of a rail or anything else.
Thanks,
benn
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